Increased mutation rates and diversity are dominant features of <i>Geobacter</i> multiheme cytochromes

Dissimilatory metal-reducing bacteria are found worldwide and encode diverse multiheme cytochromes with properties suitable for applications in bioremediation, bioenergy, and bioelectronics. We find that multiheme cytochromes involved in extracellular electron transfer show poor conservation, with significantly higher mutation rates than other elements of the proteome. This previously undescribed characteristic will limit the efficacy of standard methods of homolog annotation and database mining currently used to identify specific multiheme cytochromes. Our findings also suggest that a vast pool of undiscovered multiheme cytochromes are constantly being acquired and exchanged.